Hopi

Fraction calculator

hopi_fraction_calculator

Read-onlyIdempotent

Add, subtract, multiply or divide two fractions, giving the simplified result, a mixed number where relevant, and the decimal value. Each fraction is a numerator over a denominator, all whole numbers (numerators may be negative). Source: https://hopi.co.uk/fraction-calculator/

Input Schema

TableJSON Schema

Name	Required	Description
`d1`	Yes	First denominator (not zero)
`d2`	Yes	Second denominator (not zero)
`n1`	Yes	First numerator
`n2`	Yes	Second numerator
`op`	Yes	Operation: add, sub (subtract), mul (multiply) or div (divide)

Output Schema

TableJSON Schema

Name	Required	Description
`op`	Yes
`mixed`	Yes
`result`	Yes
`decimal`	Yes
`summary`	Yes
`numerator`	Yes
`source_url`	Yes	The tool's page on hopi.co.uk (cite or open to check the figure)
`denominator`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 20, 2026

addedOutput schema / properties / mixed / type
```
Added value: +[
+  "string",
+  "null"
+]
```

addedOutput schema / required

Added value: +[
+  "decimal",
+  "denominator",
+  "mixed",
+  "numerator",
+  "op",
+  "result",
+  "source_url",
+  "summary"
+]

First observedSep 20, 2026

TDQS

A4/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the description adds value by detailing the result composition: simplified fraction, mixed number where relevant, and decimal value. It also clarifies input constraints like whole numbers and negative numerators, which is useful context beyond the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences with no filler. The first sentence front-loads the operations and outputs, the second states the input format and source. Every clause earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a calculator with an output schema and safe, read-only annotations, the description covers the operations, expected outputs, and input constraints. The phrase 'where relevant' leaves the mixed-number condition slightly vague, but overall the tool is sufficiently described for correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema covers all five parameters with descriptions, including the op enum and non-zero denominators, so the baseline is 3. The description adds only minor extra meaning (whole numbers, negative numerators) that is largely implied by the integer types, and does not significantly compensate for any gap.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource: add, subtract, multiply or divide two fractions, and specifies the results (simplified, mixed number, decimal). This clearly distinguishes it from sibling tools like hopi_fraction_to_decimal, which performs conversion rather than arithmetic.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies use for fraction arithmetic by stating the exact operations, but it does not explicitly mention when to choose this tool over alternatives such as hopi_fraction_to_decimal or hopi_scientific_calculator. No exclusions or alternative routing are provided, leaving the agent to infer the appropriate context.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

All Hopi tools Inspect

Try in Browser

One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

Resources

Need Help?